I came across this post because I was looking for info about Terrapass. I like the comments about hybrids and how many carbon credits you could by with the extra money. But buying a hybrid is about more than just lower emissions - its at least partially about using significantly less gas and reducing the US dependence on foreign oil. Buying carbon credits doesn't reduce gas consumption as best I can figure.

But I take the point that using home ground biodiesel is good for emissions and using less gas even though diesel vehicles still have particulate matter issues (PM10, etc). How about the best of both worlds - hybrid biodiesel vehicles that can run off only electricity for short haul? Then you can plug into clean solar and wind power.

A couple parting questions:

1. I've never seen anyone say the cost of replacing Prius batteries would be as high as $11k. That sounds like FUD to me, isn't the price more like a couple of grand?

2. Its easy to argue that reusing waste bio oils (eg. cooking oil) for biodiesel is always good, but I keep hearing that most biodiesel takes more petroleum products to grow it than it replaces in demand. That goes for manufacturing fertilizers and energy for processing and farming it. This sounds like the same arguments applied to methanol/alchol based fuels - anyone got some clarity and trut about the issue?